The Chandley U.S. Pat. No. 4,982,777 issued Jan. 8, 1991, and copending Chandley application Ser. No. 628,479, now U.S. Pat. No. 5,146,973, of common assignee herewith describe methods for the differential pressure, countergravity casting of molten metal from a molten metal pool into a self-supporting, gas permeable mold disposed in a casting chamber or box wherein the mold is engaged with (e.g., immersed in) the pool, a differential pressure is established to urge the melt upwardly into the mold, the filled mold is withdrawn from the pool before the metal solidifies therein, and the filled mold is inverted to permit the molten metal to solidify in the inverted mold. A relative vacuum is maintained in the casting chamber to draw the molten metal upwardly into the mold from the pool and as the filled mold is withdrawn from the pool to prevent molten metal runout therefrom. Once the mold is inverted, the vacuum is discontinued.
These methods are advantageous in that shortened casting cycle times are achievable as a result of the reduction in the time that the mold must be immersed in the molten metal pool and the time that the differential pressure must be maintained in the casting chamber.
The Chandley U.S. Pat. No. 5,069,271 issued Dec. 3, 1991 employs a thin-walled, gas permeable mold which is supported by a particulates support media (e.g., dry foundry sand) in a casting chamber or box, the support media being compacted about the mold when the differential pressure is established in the casting chamber for countergravity casting.
An object of the present invention is to provide an improved method and apparatus for differential pressure, countergravity casting of a melt in shortened cycle times into a mold via a serpentine melt inlet passage communicated to a mold cavity thereabove for allowing withdrawal of the melt-filled mold from the melt source before the melt solidifies therein and inversion of the melt-filled mold without melt runout from the mold cavity.
Another object of the present invention is to provide an improved method and apparatus for differential pressure, countergravity casting of a melt in shortened cycle times into a mold via a serpentine melt inlet passage formed between a pair of identical refractory components, one of which is inverted and mated to the other to form the serpentine inlet passage therebetween.